I’m not crazy about this book myself, but it has some good points, and I have some respect for Nagel himself. I will review it as objectively as I can and in some detail.

It should be made clear that Nagel does not actually question the fact of evolution, merely the explanation that it has been guided by natural selection. For some reason or other, Nagel is not convinced by the power of natural selection to do this. He doesn’t really say why — it’s pretty much just an argument from incredulity. The first chapter does contain enough references to sources I hadn’t read that are supposed to support his views that it left me thinking maybe there’s something there worth looking into, but that something wasn’t given here. Mind you, the only author referenced whom I had really read was Stuart Kauffman, who surely would not support Nagel’s stance. Kauffman thinks self-organisation in addition to natural selection has had a role in evolution, but his self-organisation is something you get free as a surprising result of the known laws, not something you need to add like Nagel supposes. So Kauffman’s view mainly implies everything could have evolved more easily than Darwinism supposes — not less easily. Nagel’s stance that creationist arguments against evolution have brought out good points doesn’t really inspire confidence either, considering what I know of them.

Something like a more specific complaint from Nagel is his questioning why evolutionary explanations are accepted when there are gaps needing to be filled with supposition. The answer to this is that it’s because evolution already explains so much. The notion of evolution overlies all of modern biology and its implications span across a huge range of topics. This is part of the reason there is so ridiculously much evidence of different sorts for it. If you talk about evolution and biogeography, you find that species are spread just as you’d expect if they had spread around while evolving. If you look at molecular genetics, you can check multiple different tests there of relatedness and come up with the same results. If you consider the workings of natural selection, you can see both its possibilities and limitations embodied in the creatures it has brought about. And so on. So, evolution provides an enormous number of explanations. Between these, there is probably an even more enormous number of unexplained things, especially when going into smaller and smaller detail. What this means is that if someone just doesn’t feel satisfied with it even after knowing the details, they can always ignore the successes and point to the remaining gaps in explanations. It’s not a good idea, objectively, but it’s a way to shoehorn even the actual evidence to your doubts.

But putting aside Nagel’s incredulity towards established science, there are other questions to be answered about the scientific conception of the world. How does the scientific, mechanistic view of the world fit together with the human world of consciousness, intention and value? After introducing the general problems in the first two chapters, Nagel raises the question with first consciousness, then cognition, and then value, and argues with each that the current scientific explanations are inadequate. Instead, he proposes there might be some kind of teleological laws in nature, not an actual plan by any agent but a tendency on the level of natural law for certain kinds of things to develop. It might need to be emphasized that this is only a hypothetical solution, not one Nagel thinks must be correct.

So, in chapter 3, Nagel poses the problem of consciousness, and this he does well enough. Subjective experience and physical causality seem to be separate things in principle if not in actual reality; how could their evolution be explained? Nagel hints at his teleological solution here, and I will come back to this below.

In chapter 4, Nagel makes cognition out to be a problem for orthodox explanation. The issue seems to be that we cannot use reason to explain the origins of reason as something that is not certain, because then we would be using reason to refute itself. Instead, we’re supposed to be somehow connected to a higher objective truth that allows reasoning.

I don’t see this as a big problem. It seems to be covered by supposing that the universe universally follows certain logical and mathematical rules, and so do our minds to some extent and other aids we use in figuring things out. No matter how much we may be “merely evolved”, we could hardly be totally separate from something that governs the whole universe. As Ian Stewart and Jack Cohen put it, our minds are “figments of reality”.

It should be noted that the scientific approach does not take it for granted that certain of our evolved faculties should be trusted as such. Quite to the contrary, the modern scientific approach is based on recognising the limits of all our inborn capacities to reach the truth about the world, especially in anything more complicated than simple statements about immediate events in the environment. Science uses rigorous external methods and constant methodological doubt to slowly inch its way past human limitations that could easily be regarded as downright crippling. This all has been learnt from countless generations of mistakes. This is a point Nagel misses in general when he raises his own intuitions on a level with scientific findings, something also seen in the next chapter.

Chapter 5 on values is the worst one. Even after how questionable the previous ones have been, its philosophy is a disappointment. Indeed, it’s hard to believe the basic thesis can even be called philosophy. This time, the Darwinian explanation is seen as inadequate because it can’t explain what Nagel sees moral realism as being. That part is true enough as far as it goes: Natural selection could hardly have guided us to know independent moral truths as described here. But this is only because of what “described here” involves.

What is Nagel’s notion of moral truth? He doesn’t actually have one so much as a combination of unexplained words. In Nagel’s moral realism, moral truths are objectively true and are not made true by anything else. It just is the case that something is wrong and something is right (based on some principles that are themselves objectively true and unexplained), and that’s it. So what does it mean for something to be right, or some principle to be true? No answer can be provided. No such statement is based on anything, it just is true. It’s just “an ordinary fact,” in spite of the fact that other ordinary facts are quite different. What’s the difference between it being true or not? Only itself, and to make sure this doesn’t even mean anything in an abstract philosophical scheme, Nagel makes it clear this is not supposed to be a metaphysical statement. Why is something about value true or not? It just is. How do statements about what is right or wrong relate to our actions? Nagel talks about this but doesn’t really say anything beyond the most obvious things. With his empty starting point, he can’t.

And why does Nagel believe in this? Intuition. I mean, sure, we could just feel that pain is bad as a result of natural selection, rather than it being mysteriously objectively true. But Nagel’s intuition that it is objectively so is just so strong he accepts it instead, so suddenly what made extremely good evolutionary sense becomes a mystery. This at least is a traditional philosophical mistake: treating the contents of intuitions as indicative of fact instead of simply considering it as the fact possibly needing explanation that we have an intuition. It’s like seeing writing on the wall declaring that “Kilroy was here” and considering this as evidence, not that someone’s been vandalising the wall, but rather that Kilroy was there. There are cases where appeal to intuition makes sense, but they are not like this.

This is enough for Nagel to challenge scientific orthodoxy this time: that it can’t explain something that is completely meaningless in the first place but which he feels is true.

Philosophy is supposed to make clear what our conceptions actually mean. It’s supposed to question that which we take for granted. It’s supposed to give explanations. I don’t know how it’s even possible that a distinguished philosopher says, “This is true because it’s true, and it means itself, and I believe this because I feel like it.”

And for the record, it’s not at all impossible to actually analyse what values are, even without lapsing into subjectivism, though of course the results don’t match this kind of realism. This is just one of the chances missed by Nagel to actually give an answer to the important questions he discusses.

So, Nagel has proposed that there are a number of problems that we need something new in order to explain. Though he doesn’t give a definite view, he basically rejects a solution based on natural selection as well as a theistic one (also not for very good reasons for much of the time). The third solution he’s more favourable towards is postulating teleological laws of nature. Current scientific explanations are basically causal: things happen because other things before them have caused them. Teleology goes in the opposite direction: things happen because then they will reach certain results. This is separate from actual design in that it’s only a blind law. The kind of teleology Nagel postulates would be a tendency towards increased complexity and the creation of consciousness and cognition grasping values and other truths. As far as I can see, there’s no incoherence in this idea. However, Nagel has not managed to establish that cognition or value would demand it.

What about the one thing I admitted is a good question — that of consciousness? This question is broadly the same as the hard problem of consciousness, the question of why anything material is accompanied by subjective feeling. This is indeed a question that a view based on modern science can’t seem to answer satisfactorily. Neither can any supernatural explanation. And neither can Nagel’s teleology. What I see as the real difficult problem is that the evidence seems to clearly indicate that subjective experience plays a causal role, but also that it cannot. Subjective consciousness appears in creatures who are also capable of complicated actions, decisions, and information processing. Psychological theories are perfectly justified in postulating it a functional role. We experience it as affecting our actions, too, and we cannot function the same way if we lack consciousness of something. Further, it seems clear it has been selected for by evolution. And yet: there seems to be absolutely no reason all causal roles could not be fulfilled without an accompanying subjective feeling. Clearly this is not how the world actually works, but why does it work the way it does? Why are certain physical/causal phenomena accompanied by subjective feeling?

This, to put it briefly, is the problem. Clearly, explaining it as a coincidence would be hugely problematic. Certainly there could just be laws of nature that state that consciousness accompanies some material things even though it wouldn’t otherwise have to. But that those should be just the places where it appears to be needed? This would be an enormous coincidence, and the idea is not at all believable. Well, postulating that there is a teleological law that causes the same thing would be little better. It would be saying that even though there appears to be a reason why things are as they are (consciousness is necessary), actually the only reason is that there is a law that says things will be like that.

The hard problem is a real problem, but it’s so hard it’s a problem for everyone. I know of nothing like a satisfactory solution so far. So Nagel is not justified in postulating another equally hapless “explanation” in place of the scientific one that works otherwise. In fact, people like him are only making it harder for the rest of us to get this problem recognised, as it gets confused with general incredulity about evolution and suchlike because of one’s “intuition”.

It seems that Nagel was simply the wrong person to write a book on this topic. Asking how the scientific world view and things left outside it fit together would require the ability to cross such borders in imagination, whereas Nagel seems inclined to see everything as sui generis and incapable of explanation through anything else. This is why arguments like this leave me cold in general. Those who can imagine the connections between the different aspects of the world give fascinating and contentful accounts of their views. Those, like Nagel, who do not believe in the compatibility, merely assert its impossibility without at all disproving these more interesting and fruitful views. Current scientific orthodoxy may be wrong, some things may be inexplicable from current physics, the world may turn out to have multiple irreducible levels… But there’s no great problem in the current view pointing to this, at least judging from how those arguing that there is always seem to be arguing from their own lack of imagination. The exaggerated stereotype of this are the creationists posing “hard” questions challenging evolution that have been easily answered a million times, but here we see it can also be done in a more thoughtful manner and on a philosophical level.

So if most of these questions can be answered, do I have an alternative in mind that does so? Yes. I definitely recommend reading Nicholas Maxwell’s The Human World in the Physical Universe: Consciousness, Free Will, and Evolution instead of this book. Maxwell doesn’t question the scientific orthodoxy out of his personal intuitions, but he raises the same general problem of the place of, well, the human world in the physical universe. He also provides some actual answers. He’s complementing science with philosophy instead of trying to replace it. (Mind you, he’s actually very critical of science in a different way, but not its factual results.) Others have done similar work, but this book by Maxwell is most directly concerned with the good questions raised by Nagel. Maxwell still can’t answer the hard problem — but neither can anyone else.

I will be the first to say reductive materialism must not be allowed to be the only approach to the world. We must not forget things like value and humanity. The clash between the views seems to be a peculiarly modern phenomenon, brought about by a move from a mythical and inherently meaningful world view to a scientific one where the place of meaning is not clear. These are some of the most important questions we face, but that doesn’t mean just any answers will do. Unnecessarily affirming the divide between science and humanity is not the way to go. We can build views of the world as both scientific and meaningful, and hopefully change the perception that there is a gap. This kind of explanation should really be able to fulfill Nagel’s stated goal of integrating the human aspects of nature as parts of it. Hopefully, we can even solve the hard problem without having to overhaul everything. Nagel asks some of the right questions, but questioning science in order to answer them gets him no good results.